A conventional nailing machine using compressed air as a power source is adapted so that a hammering piston is slidably accommodated in a hammering cylinder disposed in a housing, that the hammering piston is driven by supplying compressed air into the hammering cylinder, and that a nail supplied into an ejection opening in a nose portion is hammered out therefrom by a driver integrally mounted on the hammering piston toward a member to be nailed. The nose portion, in which the ejection opening for slidably guiding the driver is formed, is connected to a lower portion of the housing. An aperture opened toward a rear side of the nose portion so as to supply a nail into the ejection opening is formed in the nose portion. Connected nails accommodated in a magazine are supplied into the ejection opening by a nail supply mechanism through the aperture.
Also, a main valve is provided at the top end of the hammering cylinder. The opening/closing operations of the main valve are performed by using a trigger valve that is operated by a manually operatable trigger lever. Thus, compressed air is introduced into the hammering cylinder to thereby drive the hammering piston. A contact member, which is projected frontwardly from the ejection opening and is operated in contact with the member to be nailed, is disposed at an end part of the nose portion in which the ejection opening is formed. The trigger valve is activated on the condition that this contact member is operated in contact with the member to be nailed, and that the trigger lever disposed at a base part of a grip portion is manually operated. Thus, a safety mechanism enabled to prevent the trigger valve from being unexpectedly activated is constituted. Further, the end part of the nose portion, in which the ejection opening is formed, is divided thereby to form a separate nose top member. The contact member is constituted as a contact nose portion serving also as the nose top member. Thus, even in a case where the housing of the nailing machine and the nose portion are upwardly moved due to a reaction phenomenon caused when a nail is hammered, the contact nose portion maintains contact with the member to be nailed. Thus, a driver mark phenomenon, that the driver scratches the member to be nailed due to the misalignment between the driver and the head of a nail, is prevented (see, for example, JP-A-2002-337066).
Meanwhile, when a foremost one of the connected nails, which are connected together and supplied into the ejection opening, is hammered out therefrom by the driver, the following phenomenon occurs. That is, the foremost nail is hammered out therefrom so that a tip end portion of the foremost nail leans to the rear side thereof due to resistance caused at the disconnection between the foremost nail and the subsequent nail. To prevent a nail, which leans in this manner, from being hammered out to the rear side, the conventional nailing machine is configured so that a guide slope, which contacts with a tip end portion of the nail so as to guide the tip end portion of the nail toward the inside of the ejection opening, is formed at a bottom edge portion of the opening, and that the contact nose portion is placed at a lower part of the guide slope so as to prevent the contact nose portion from interfering with the guide slope of the nose portion.
The placement of the contact nose portion at the lower part of the guide slope of the nose portion in the aforementioned nailing machine results in that an end portion of the ejection opening formed in the contact nose portion is downwardly disposed. This requires an increase of the length of the driver hammering the nail for that. In a case where the driver is formed by being extended downwardly, the bottom position of the driver, which corresponds to the top dead center of the hammering piston, is downwardly shifted. Thus, it is necessary to upwardly shift the position of the top dead center of the piston. Consequently, the conventional nailing machine has drawbacks in that the placement of the nose top member downwardly from the guide slope of the nose portion results in large overall height and weight of the mailing machine adapted to hammer a nail having the same length, and that such an ill-balanced nailing machine impairs the workability thereof.
Further, the length of the nose to the end thereof is set according to that of nails to be used. In a case where a nail pickup slope is formed at the bottom of the nose portion, a component used as the nose portion, whose length is set according to the length of a nail to be used, should be formed as a component inherent in the machine. Consequently, the conventional nailing machine has another drawback in that the manufacturing cost thereof is increased.